Comparative measurement of D- and L-lactic acid isomers in vaginal secretions: association with high-grade cervical squamous intraepithelial lesions

Abstract

Purpose: Identification of low-cost protocols to identify women at elevated susceptibility to develop cervical intra-epithelial abnormalities would aid in more individualized monitoring. We evaluated whether quantitation of the D- and L-lactic acid isomers in vaginal secretions could differentiate women with normal cervical epithelia from those with a low (LSIL) or high (HSIL) grade squamous intraepithelial lesion or with cervical cancer.

Methods: Vaginal samples, collected from 78 women undetgoing cervical colposcopy and biopsy, were tested for pH, bacterial composition by Gram stain (Nugent score) and concentrations of D- and L-lactic acid by a colorimetric assay.

Results: Subsequent diagnosis was 23 women with normal cervical epithelium, 10 with LSIL, 43 with HSIL and 2 with cervical cancer. Vaginal pH and Nugent score were comparable in all subject groups. The concentration of L-lactic acid, but not D-lactic acid, as well as the L/D-lactic acid ratio, were significantly elevated (p < 0.01) in women with HSIL and cervical cancer.

Conclusion: Comparative measurement of vaginal D- and L-lactic acid isomers may provide a low-cost alternative to identification of women with an elevated susceptibility to cervical abnormalities.

Keywords: Cervix uteri; Lactic acid isomers; Squamous intraepithelial lesions; Vagina.